An ultrasonic diagnostic apparatus is an apparatus that brings a probe into contact with the body surface of a test subject, repeatedly irradiates an observation sight with ultrasonic waves via the probe, receives a reflection echo signal generated from the test subject, and reconstructs an ultrasound image (e.g., a tomogram).
In such ultrasonic diagnostic apparatus, when the ultrasonic waves are continuously transmitted while the probe is separated from the body surface of the test subject (called “left in the air” below), the energy of the transmitted ultrasonic waves changes to thermal energy and the temperature in the vicinity of the surface of the probe (e.g., the ultrasonic wave transmittance window, etc.) rises. As a result, sometimes deterioration arises, such as a member like rubber that forms the probe separating, because a thermal heat cycle arises in the probe.
In order to prevent such a temperature rise, conventionally the transmission of the ultrasonic waves has been automatically stopped when the operation console has not been operated for a certain period of time or greater. For example, a timer is activated when an operation has not been conducted, it is assumed that the probe is left in the air when the timer counts a preset period of time, and the temperature of the probe is prevented from rising by stopping the transmission of the ultrasonic waves (hereinafter referred to as freezing) (Patent Document 1: Japanese Patent Application Publication No. 64-68239).
Also, when a change in the temperature of the surface of the probe is recorded and the temperature rise is calculated and the temperature rise exceeds a stipulated value, the transmission output is set to be within the stipulated value (Patent Document 2: Japanese Patent Application Publication No. 2000-5165).
However, according to the ultrasonic diagnostic apparatus described in Patent Document 1, when the operation console has not been operated for the certain period of time, it is assumed that the probe is left in the air, so that sometimes the judgment that the probe is left in the air is not accurate. For example, when the probe is brought into contact with the test subject and diagnosis is conducted over a relatively long period of time, it is assumed that the probe is left in the air and that freezing has started because there is no command from the operation console, which is a drawback.
Also, according to the ultrasonic diagnostic apparatus described in Patent Document 2, there is no sense of real time and the transmission output cannot be set before the temperature of the probe rises. Thus, the ultrasonic diagnostic apparatus is lacking in safety.
The problem of the present invention is to accurately judge that the probe is left in the air and suppress a rise in the temperature of the probe.